In commercial aircraft wing tip extensions are often installed for the purpose of improved efficiency due to a reduction of lift-induced drag and due to the increased lift generated at the wing tip. While wing tip extensions are usually designed for cruise flight conditions they may comprise an unwanted stall behavior during takeoff and landing. While the wing itself usually comprises high lift devices, e.g. in the form of slats arranged at the leading edge with the purpose of delaying the stall of the trailing wing with respect to the angle of attack at which the main wing stalls without the use of a high lift device, a protection of the wing tip extension would necessitate a rather complex kinematics at a wing tip extension due to the varying complex curvature and the available small assembly room. Hence, wing tip extensions are commonly unprotected in terms of leading edge high lift device installment.
In the state of the art there are different solutions for improving the stall behavior of an unprotected wing tip extension. For example, it is known to install passive leading edge fences located inboard of the wing tip extension. However, it is questionable if this measure is capable of completely eliminating the stall in certain flight envelop bandwidths. It can however be assumed that it rather prevents localized stall areas from spreading further outboard.